1. Field of the Invention
This invention relates to the field of ground proximity warning systems, particularly to systems that warn of excessive aircraft altitude loss after take-off or during a go-around after a missed approach, and more particularly to systems optimized for rotary wing aircraft such as helicopters.
2. Description of the Prior Art
Ground proximity warning systems that warn of aircraft descent after take-off or during a go-around after a missed approach are known. Examples of such systems are disclosed in U.S. Pat. Nos. 3,946,358; 3,947,808; 3,947,810 and 4,319,218 assigned to the assignee of the present invention. The systems disclosed in the '358 and '808 patents provide a warning if the descent rate of the aircraft exceeds a predetermined rate below a given altitude, and the systems disclosed in the '810 and '218 patents generate a warning if the altitude loss exceeds a predetermined value before a predetermined altitude is reached.
While these systems do provide a way to warn the pilot of an aircraft of a hazardous condition resulting from an excessive sink rate or from an excessive altitude loss during the take-off or missed approach phase of operation, these systems are designed for use in transport aircraft, and not for use in highly maneuverable rotary wing aircraft such as helicopters whose flight and operational characteristics are entirely different than those of transport aircraft. Consequently, the systems designed for transport aircraft can generate nuisance warnings during certain normal operational conditions of a rotary wing aircraft, and provide no warning or an inadequate warning during other flight conditions.